Segue to new topic: Edge connectors

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Glenn Roberts

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Jun 3, 2021, 3:13:37 PMJun 3
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Enjoyed the ShadowTron video…

 

In there he discusses the 25-pin Molex edge connectors and how a while back some of us (not me unfortunately) bought up some stock. Those Molex connectors are now listed (at least by Mouser) as “obsolete”

 

Verical says they have 62 in stock with minimum order quantity of 7.  $5.18 each.  I’ve not dealt with this vendor before.

 

 

The edge connectors that Norberto usually recommends are a Samtec product (BCS-125-L-S-HE).  Currently both DigiKey and Mouser are out of stock with 8-10 week lead time

 

Sager has 278 in stock @$4.59 per unit.

 

Also Powell at same price

 

Those are two vendors that I am also not familiar with…

 

  • Glenn

 

 

 

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of norberto...@koyado.com
Sent: Thursday, June 03, 2021 2:40 AM
To: se...@googlegroups.com
Subject: RE: [sebhc] H8 8080A/Z80 64K RAM ORG0 BRD

 

Shadow Tron documented this 8080A/Z80 64K board in detail. He created 6 chapters which I enjoyed watching a lot. I need to add a link to my website.

 

https://www.youtube.com/watch?v=xpvd9NF3iq0  - chapter 1.

 

On this board the team rally behind it and it is well documented. I thank everyone that helped.

 

Norberto

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Mitchell Smith
Sent: Wednesday, June 2, 2021 10:35 PM
To: SEBHC <se...@googlegroups.com>
Subject: Re: [sebhc] H8 8080A/Z80 64K RAM ORG0 BRD

 

I watched a couple youtube videos from Shadow Tron. He built one of these. I love the memory backup battery. Great feature.

 

 

On Wednesday, June 2, 2021 at 12:06:23 PM UTC-7 Norby wrote:

The beauty of this board is that it works with any H8 monitor and CPU’s (8080A, Z80). As I can select any memory region, it can be used to debug older memory boards. For example, I select the first 8K region for this board, skip another 8K region, and enabled the older memory boars above this region to debug it. Then I use the H8 front panel monitor to debug such older memory board.

 

This board works fine up to 10MHz.

 

Norberto

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Glenn Roberts
Sent: Wednesday, June 2, 2021 2:42 AM
To: se...@googlegroups.com
Subject: Re: [sebhc] H8 8080A/Z80 64K RAM ORG0 BRD

 

This is a nice board. I didn’t appreciate the value of the on-board battery backup until I started using this with the H-8-5 serial port and front panel load and dump functions. This lets you load programs into RAM at any location and run them from the front panel by setting the PC and hitting GO. No OS or boot process required. Let’s you load up multiple programs and quickly run them, e.g. for demo purposes and at computer fests.

Sent from my iPad

 

On Jun 2, 2021, at 1:23 AM, Mitchell Smith <kb3...@gmail.com> wrote:



Yes, that's the one.

Just to confirm, I have a regular H8 with the 8080 CPU. No modifications.

 

Also looking for an extender board if you have one of those available.

 

Thanks a bunch!

Mitch

 

 

On Tuesday, June 1, 2021 at 9:07:27 PM UTC-7 Norby wrote:

Yes, I do have some spares. 

 

You are looking for this one; correct?

 

H8 8080A/Z80 64K RAM ORG0 BRD . KiCad files, Gerber files, and Schematics. 8080A-64K-V1_3.rar - Gerber files

 

 

Thanks,

Norberto

 


From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Mitchell Smith <kb3...@gmail.com>
Sent: Tuesday, June 1, 2021 8:05 PM
To: SEBHC <
se...@googlegroups.com>
Subject: [sebhc] H8 8080A/Z80 64K RAM ORG0 BRD

 

 

I'm thinking about building the H8 8080A/Z80 64K RAM ORG0 board.

 

Does anyone have a PCB available for sale?

 

If not I may place an order with OurPCB.

 

Thanks!

 

Mitch

 

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Glenn Roberts

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Jun 3, 2021, 3:16:19 PMJun 3
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And Terry Smedley showed me an example where he used multiple of the smaller Molex units (which are still available) . see attached.

 

Terry says Molex part numbers: 22-16-2xx1, xx=number of positions

 

Digikey stocks 4,5,6,10 position

Mouser stocks others

image001.png
20201015_100816_resized_1.jpg

Mitchell Smith

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Jun 4, 2021, 12:26:24 AMJun 4
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I found the connectors at Avnet. Says they have 278 in stock and ships in 2 weeks. So maybe they're not actually in stock.

Terry Smedley

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Jun 4, 2021, 10:00:37 AMJun 4
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Amazon (marketplace seller) has a listing for 5-packs of 22-16-2251 connector for $33.31.  I ordered one set to confirm the vendor's description and performance.


Terry

Steven Hirsch

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Jun 4, 2021, 11:57:11 AMJun 4
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> Verical says they have 62 in stock with minimum order quantity of 7
> <https://www.verical.com/pd/molex-headers---pcb-receptacles-22162251-768246?utm_campaign=octopart_2020&utm_currency=USD&utm_keyword=22162251&utm_medium=aggregator&utm_content=inv_listing&utm_source=octopart>
> . $5.18 each. I’ve not dealt with this vendor before.

They appear to be associated with Arrow, who managed to take 6+ weeks to fill
the last order I placed with them (last February).

Glenn Roberts

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Jun 7, 2021, 10:58:40 AMJun 7
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At the risk of beating a dead horse…

 

The Molex connectors ending in ‘0’ are probably fine for our purpose, slightly thinner gold coating.  But ½ the cost or less.  So to build up a 51-positoin edge connector you could, say, do 3 16-pin connectors and a 3-pin one, or 3 15’s and a 6.  Then use a Molex polarizing key to block the position in the middle (handy for preventing power supply burnout from mis-aligned card!)

 

From Mouser:

3x15 pins:            538-22-16-2150                 $2.10                     $6.30

1x 6 pins:             538-22-16-2061                 $2.39                     $2.39    

TOTAL/board: $8.69

 

Or

 

3x 16 pins:           538-22-16-2160                 $2.50                    $7.50

1x 3 pins:             538-22-16-2031                 $1.12                     $1.12

TOTAL/board: $8.62

 

I believe the connector keys are Mouser # 538-15-04-0219.  They have plenty of stock on all of the above components.

 

Using the connector key to block the center hole is a little more elegant than Gorilla-gluing a shorting block in between the Samtec connectors 😊

 

Thanks to Terry Smedley for suggesting this approach.

 

  • Glenn
image001.png

Gery Kissel

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Jun 7, 2021, 5:34:30 PMJun 7
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You can partially blame me for Mouser being out of stock of Samtec product (BCS-125-L-S-HE).  I received 2 last week.  I think they were down to 9 when I ordered.

I now have all the parts needed to start my V4 build and was getting organized today.  Regarding the installation of these 2 headers, I assume that the headers install using the right most row of holes for the headers?
I know, probably an obvious question.
Any photos of completed V4 boards for motivation and reference?

Thanks,
Gery

glenn.f...@gmail.com

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Jun 7, 2021, 9:19:20 PMJun 7
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Or blame me.  I just received 4 of them from Mouser which, at the time I ordered, depleted their stock   I wasn’t observant enough in my previous DigiKey order and didn’t realize those were back ordered, so some day 6-8 weeks from now I should have more !

 

The Samtec edge connector should be mounted as close to the edge of the board as possible with the shrouded hole openings toward the edge. The holes on the back of the connector are open showing the metal contacts.  I haven’t seen a picture of an assembled 4.0 board yet but will gladly share mine once it’s complete (still waiting on some components).

 

Norberto has a picture of the rev 3 board which shows the edge connector installed:

 

http://koyado.com/Heathkit/H8-Z80-64K-RTC-ORG0-V3.html

 

Both the 3.x and 4.x boards have accommodations to install an optional header row behind  the edge connector.  I’m guessing this is to simplify testing and signal measurement (?) or I suppose could be used in the future to support a piggyback board?

Terry Smedley

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Jun 7, 2021, 9:45:42 PMJun 7
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Completed v4 CPU.  Molex 22-16-2251 bus connectors.  You can also see an 8-pin header installed to provide access to the IRQ lines, as Glenn noted.  Low-profile ZIF socket used for the EEPROM.  An I2C temperature sensor is attached to the surface of the Z80 CPU.

Terry

Complete Front DUART.jpg
Complete Front.jpg

Glenn Roberts

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Jun 7, 2021, 9:55:58 PMJun 7
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Terry: curious if you see anything interesting from the temp sensor? Does the z80 ever get warm enough to raise any concern?

Sent from my iPad

On Jun 7, 2021, at 9:45 PM, Terry Smedley <terry....@gmail.com> wrote:

Completed v4 CPU.  Molex 22-16-2251 bus connectors.  You can also see an 8-pin header installed to provide access to the IRQ lines, as Glenn noted.  Low-profile ZIF socket used for the EEPROM.  An I2C temperature sensor is attached to the surface of the Z80 CPU.
To view this discussion on the web visit https://groups.google.com/d/msgid/sebhc/50467059-482d-49fa-b8b2-bb679caff2f6n%40googlegroups.com.
<Complete Front DUART.jpg>
<Complete Front.jpg>

Terry Smedley

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Jun 7, 2021, 11:12:38 PMJun 7
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Nothing worth monitoring since becoming Collado-ized.  

First, I'll acknowledge that sticking an ambient temperature sensor on top of a plastic case with double-stick tape is just a tad shy of an engineering-quality measurement of CPU temperature.

With the Trionyx Z80 CPU card running at 4MHz, I would typically see temperatures around 100F-102F.  I used 104F as the trip point to send case fans to higher RPM.  That CPU was a Mostek Z80A, date code 8207.  

With the v4 CPU card running at 16MHz, I see temperatures about 84F.  That CPU is a Zilog Z84C0020PEG.

Given how cool the H8 is running, and how little power is being consumed (all of 1.4A on the +8v line), the elaborate temperature sensor/fan control setup I used with the original equipment setup is, well....completely unnecessary now.  But it's still fun to have the telemetry display to have something to watch.

Terry
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Glenn Roberts

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Jun 8, 2021, 8:51:28 AMJun 8
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Perhaps a nit but Terry’s photo actually shows the connector 180 degrees opposite of the way I’d recommend install.  Here’s the side that should face toward the edge:

 

 

And here’s what the back of the connector looks like:

 

 

 

It’s easy to put these in backwards (voice of experience), though I doubt there’s any real problem with it installed that way.

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Terry Smedley
Sent: Monday, June 07, 2021 7:40 PM
To: se...@googlegroups.com

Subject: Re: [sebhc] Re: Segue to new topic: Edge connectors

 

Hi, Geri

 

Your Samtec connectors should look like this photograph, with two rows of solder pins.  They are installed as shown in the top of the photo (not the v4 card, but similar to it).  Hope this helps!

 

Terry

 

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Glenn Roberts

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Jun 8, 2021, 9:44:12 AMJun 8
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Beautiful build Terry.  the ZIF is a nice touch.  Also I note use of machined sockets (good) but dual wipe for the H37 I/O interconnection, which is subject to more frequent connection/disconnection (clever!).  Plus as you’ve noted the extra header for access to IRQs.

 

On the edge connectors I note that Mouser must not sell many (are we the only buyers?)  they’re ordering in pretty small quantities:

 

 

For Digikey they categorize this as a “value added” item:

“This is a value added item which we custom assemble or package. In most instances we can assemble or package this item specifically for your order and ship it the same day. If you place this item on your order it will show up backordered. We will contact you if we are unable to fulfill your order”

In the past I’ve gotten these right away despite this categorization, but this time I seem to have to wait (and they didn’t contact me ).  I chatted with a help agent at DigiKey and I think I sort of understand.  She says they are “put together in the warehouse” and ordered “on demand”.  It sounds like they keep shells and contacts in stock and make these up to length based on demand?  Perhaps they’re extra busy now?  She told me estimated date for my backorder is about 2 weeks… there will be an extra shipping fee for that package.

 

It looks like you’ve used the Monolithic Power Systems DC-DC converters

My only caveat would be for anyone who wants to power their system with a PC/ATX style power supply I would think there could be an issue as these converters require a minimum input voltage of 6.5V.  the Pololu will work with a wider range of input voltages (2 to 16)…  but for straight replacement of the 7805 the MPS ones are a good way to go; cool and cheap!

  • Glenn

 

 

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Terry Smedley
Sent: Monday, June 07, 2021 9:36 PM
To: se...@googlegroups.com

Subject: Re: [sebhc] Re: Segue to new topic: Edge connectors

 

Completed v4 CPU, with and without DUART serial board.  Bus connectors are Molex 22-16-2251.  Low profile ZIF socket used for EEPROM.  

 

Terry

 

 

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Gery Kissel

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Jun 8, 2021, 4:02:35 PMJun 8
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Well I am glad I asked my question.  Thanks for the photos and information.
Good info!

I plan to go old school and use linear regulators for this project.  I have used the regulator replacement at the link below in my Heathkit GC1000 Most Accurate Clock I refurbished 1.5 years ago.  The 5V regulator in that clock was pushed HARD.  You could fry an egg on the cover of the clock.  There was a big heatsink for the regulator which was a good source of heat to bake the electrolytics that surrounded it.
Anyway, I substituted this for the regulator and have had no regrets.  The clock is only warm enough to let you know it working. 
This company also makes 12V regulators.


Regards,
Gery

Norberto Collado

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Jun 9, 2021, 1:28:27 AMJun 9
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Hello Terry,

 

Can you send me the schematics on how you control the Fans RPM’s?

 

Thanks,

Norberto

 

Terry

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Norberto Collado

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Jun 9, 2021, 2:00:14 AMJun 9
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On another email thread with Terry, he helped me identify a new 2x25 connector for $3.84 each, which allows to move back the board or to the front depending on space needs between each board. I’m planning to use them for the mini-boards. I will order a few to test out.

 

A screenshot of a computer

Description automatically generated with medium confidence

3M 6850 series with gold contacts, tin posts: https://www.digikey.com/short/8d458fhv

 

 

3M 8550 series with gold contacts, gold posts: https://www.digikey.com/short/p3b3wddf  ; more expensive

 

Thanks,

Norberto

 

Example:

 

A close-up of a circuit board

Description automatically generated with medium confidence

 


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Terry Smedley

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Jun 9, 2021, 2:43:06 AMJun 9
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Norberto:

(Red face) Not a very impressive schematic or circuit.  I just used an 8255 output bit to switch a Form "C" relay from +8v to +12v for the power supply to the fans.  +8v I picked up from the H8 bus pins 1/2.  +12v I stole from wherever I could easily get it - from the H17 power supply, the H8-4 card, or the AM9511 APU card.  The 8255 output bit is controlled by a background process (chained into the 2ms tick interrupt) that monitors the I2C temperature sensor mounted on the CPU every 512 ticks or ~1 second.  I more or less arbitrarily chose 104F as the trip point, and require five successive readings above 104F to switch to +12v on the fans.  When the temperature drops below 102F for five successive readings, the fan supply is dropped back to +8v.  

A 2N3904 does the switching, a relay with 5v coil is used, with a transient suppression diode across the coil.  8255 input bits monitor the fan tachometers.

And your fuel-efficient boards have made all of this no longer necessary.  :-)

Terry
IMG_20210608_0002.jpg

Norberto Collado

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Jun 9, 2021, 10:21:49 AMJun 9
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Very nice and thank you.

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Steven Hirsch

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Jun 11, 2021, 4:12:23 PMJun 11
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On 6/3/21 3:13 PM, Glenn Roberts wrote:

> Verical says they have 62 in stock with minimum order quantity of 7
> <https://www.verical.com/pd/molex-headers---pcb-receptacles-22162251-768246?utm_campaign=octopart_2020&utm_currency=USD&utm_keyword=22162251&utm_medium=aggregator&utm_content=inv_listing&utm_source=octopart>
> . $5.18 each. I’ve not dealt with this vendor before.

FYI: I received (7) of these today after ordering middle of last week. They
look great and fit perfectly. Now I have enough for three boards with a spare
left over :-).

Time to put a gun to my head and order all the rest of the parts to build my
CPU and disk controller..


Steve

Glenn Roberts

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Jun 21, 2021, 6:39:49 AMJun 21
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Norberto: would this connector allow the CPU board to be set back a bit in the first slot?  With the “classic” front panel (FP) board and the latest Z80 CPU boards there’s really not enough space and I have to waste the first slot by setting the CPU in slot 2…  Pretty sure once we have the new front panel there will be a lot more breathing room between the CPU and the FP board?  The “rats next” of wire in the original H8 design has always been an issue. 

image001.png
image002.png

Terry Smedley

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Jun 21, 2021, 11:02:11 PMJun 21
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Glenn:

The edge connectors that Norberto referred to won't improve the CPU clearance with the front panel - they would actually make it worse.  These edge connectors are similar (not identical) to what Heath used to minimize the card footprint in the half-slot at the back of the H8.  Was there any card other than the Heath Org-0 card that went specifically to that slot?

Terry

norberto...@koyado.com

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Jun 22, 2021, 1:42:04 AMJun 22
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On the Front Panel board, perhaps we can add an spacer between the board and the bracket that holds the front panel in place. That should give you more clearance between the CPU and the H8 FP.

 

Norberto

Verical says they have 62 in stock with minimum order quantity of 7.  $5.18 each.  I’ve not dealt with this vendor before.

norberto...@koyado.com

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Jun 22, 2021, 2:42:35 AMJun 22
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Or do you want me to add another connector to the new H8 backplane to move the CPU board away from the Front panel. I’m almost ready to order the new backplane for testing.

 

Subject: RE: [sebhc] Re: Segue to new topic: Edge connectors

 

On the Front Panel board, perhaps we can add an spacer between the board and the bracket that holds the front panel in place. That should give you more clearance between the CPU and the H8 FP.

 

Norberto

Verical says they have 62 in stock with minimum order quantity of 7.  $5.18 each.  I’ve not dealt with this vendor before.

Glenn Roberts

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Jun 22, 2021, 4:53:43 AMJun 22
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I’d say at this point don’t reopen the design on the backplane. Pretty sure the new front panel design will eliminate this crowding issue?

Sent from my iPad

On Jun 22, 2021, at 2:42 AM, norberto...@koyado.com wrote:


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